The invention relates to a sterilization testing apparatus comprising a housing with a testing chamber, an indicator placed therein, and a supply line for supplying the sterilizing medium.
Sterilization apparatuses are used to be able to decide with adequate certainty after a sterilization whether the sterilization procedure was successful.
Preferably a gaseous or vaporous medium is provided as the sterilization medium, e.g., steam, ethylene oxide, or formaldehyde. In particular with so-called steam sterilizers like those employed in hospitals, long tubes and medical tools and equipment must be able to be sterilized with a probability approaching certainty. In the case of steam sterilizers, as a rule the sterilizer is evacuated prior to supplying the e.g. normally 121° C. or 134° C. hot saturated steam. The effect of this is that the sterilization agent travels unimpeded through the residual gases remaining in the sterilization item to the locations to be sterilized. For this, it is necessary that the testing chamber with the indicator is connected to the atmosphere of the steam sterilizer only via a supply line that is very long relative to its cross-section.
The coupling of the supply line to the testing chamber represents a weak point in the sterilization testing apparatus.
Thus, in accordance with DE 43 19 397 C1 it is established that given the aforesaid conditions damage to the supply line is conceivable. The damage can begin at the connection or coupling between supply line and testing chamber. Even minor leaks can be sufficient for the path of the ambient sterilization atmosphere to be shortened, while circumventing the longer path through the supply line, so that the indicator located in the testing chamber incorrectly indicates complete sterilization and/or adequate sterilization conditions.
The connection from the supply line to the testing chamber is also frequently found to be the weak point of the testing system because the supply line hangs loose on the testing chamber and/or its container and this coupling point is mechanically stressed when the testing body is used.
In accordance with DE 43 19 397 C1, for these reasons the supply line embodied as a tube is replaced by a stopper made of porous material that makes it more difficult for the sterilization agent to flow into the testing chamber like a labyrinth seal. When used frequently, this solution has the disadvantage that the stopper acts not only like a labyrinth but also like a barrier to the sterilization agent.
With DE 197 24 158 A1, the described disadvantages are intended to be rectified in that a sterilization testing apparatus is created with a supply means embodied as a long extended tube, whereby the supply line is closely packed—mechanically immobile—on the container. However, the disadvantage of this solution is that the supply line still is not protected from damage, even if it is practically securely connected to the container of the testing chamber and thus the connecting parts are no longer subject to mechanical stress. In addition, producing this proposed solution is very complex.
The known sterilization testing apparatus have an additional disadvantage.
The indicator must be placed in the sterilizer by the operator prior to the sterilization procedure and must be removed again for documentation purposes after the sterilization. As a rule, the testing chamber is closed by a cover that can be inserted or screwed on. These covers generally have a seal that is intended to prevent the short-circuit of the surrounding sterilization agent and testing chamber and must be tested regularly and replaced if necessary. If the cover and/or the seal has a leak, it is not possible to check whether the indicator is displaying successful sterilization due to the leak in the cover or the seal or due to correct sterilization. Likewise, it is possible that the indicator is pinched between the testing chamber wall and the cover when the cover is screwed or placed on.
With sterilization apparatus, it is necessary that an indicator is connected to the atmosphere of the sterilizer only through a supply line that is very long relative to its cross-section. Using the interaction of the sterilization medium, with a supply line that is very long relative to its cross-section, with the indicator it can be demonstrated in models that even hollow spaces and tubes or porous materials are acted upon or penetrated with the sterilization medium.
In DE 102 13 066 A1, a solution for such a sterilization apparatus is proposed in which a hollow diffusion space is formed from two thin films (wall elements) by a protuberance, at least in one of the films, and the second film closes off this hollow diffusion space from the outside so that it is sterilization medium-tight. An indicator is arranged in the hollow diffusion space.
These solutions provide a number of advantages over the existing systems. For one thing, there is no coupling point between testing chamber and supply line, and for another thing it is designed as a disposable item, which greatly simplifies handling of the system.
The disadvantage of this solution is that the supply line tube, in this case called the hollow diffusion space, is subjected to mechanical influences in the sterilization chamber with no protection. The effect of even such a very slight porosity of the hollow diffusion space is that the sterilization medium travels to the indicator, having circumvented the complete path via the entire diffusion segment.
Another disadvantage is that the indicator cannot be removed from the testing body. Although DE 102 13 066 A1 does describe that the complete system is to be archived, given the dimensions as suggested in prEN13060: 2002 and/or in EN 867-5 4.5, the testing system is several millimeters thick, so that the testing system is not suitable for complete documentation.